Siemens SIMATIC PCS 7 Operating Manual page 166

Configuration with Safety Matrix
8.3 Organizing matrices into different shutdown groups
7. Compile the S7 program.
The compiler will create the newly generated shutdown group and the additional runtime
groups @F_IN_<OBNr>_xx and @F_OUT_<OBNr>_xx.
Note
Please note that if the matrix CFC shutdown groups are subsequently moved or the safety
program is subsequently divided into shutdown groups, the amount of additional effort may
be considerable in terms of the change configuration work involved. For this reason, you
must make sure that division into shutdown groups takes place at the start of configuration
and that the F-signal modules are assigned to shutdown groups.
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Compendium Part B - Process Safety (V8.2)
Operating Manual, 07/2016, A5E35031794-AB